For patients with metastatic spinal cancer, more limited tumor resection paired with very high-dose radiation treatments delivered using stereotactic body radiotherapy (SBRT) marks a major shift in treatment. Previously, the standard was highly invasive spinal surgical procedures and the use of low-dose conventional external beam radiation therapy regimens.¹ The conventional approaches to treatment have traditionally been highly morbid and often involve circumferential tumor resection, conventional external beam radiation therapy over as many as 10 to 15 sessions, and spinal surgery aimed at achieving bone fusion. Brad Zacharia, MD, MS, director, neuro-oncology and skull base surgery, Penn State Neuroscience Institute, notes, “With more aggressive resection and stabilization paired with low-dose radiation, the outcomes are often poor, with long periods of recovery, neurologic complications and inadequate tumor control.”

“Championed by Mark Bilsky, MD, at Memorial Sloan Kettering Cancer Center and now implemented at Penn State Health Milton S. Hershey Medical Center,” Dr. Zacharia explains, “this is a very different way of thinking about metastatic tumors of the spine. Tumor resection is aimed at decompression, stabilization and creating room around the spine to allow safe delivery of high-dose radiation. The main means of tumor control is image-guided SBRT rather than surgical resection.”

Figure 1: Axial slice of T2-weighted MRI. Planning treatment volume is highlighted in red. 100% isodose line delineating the area receiving the presciption dose is highlighted in yellow. Radiation dose is purposely sculpted around the spinal cord.

Figure 2: Axial CT slice of a tumor involving the cervical spine. Planning treatment volume is highlighted in red. 100% isodose line delineating the volume receiving the prescription dose is highlighted in yellow.

Figure 3: Coronal slice of T2-weighted MRI showing the treated lesion highlighted in red. The yellow line denotes the volume receiving the prescription dose. The green line denotes the volume receiving 90% of the prescription dose.

Advances in radiation oncology have allowed development of newer, more accurate and more rapid radiation delivery systems. “We acquired a TrueBeam™ (Varian Medical Systems, Palo Alto, Calif.) stereotactic system, which allows us to deliver radiation almost anywhere it is needed in the body,” explains Jennifer Rosenberg, MD, radiation oncologist, Penn State Cancer Institute. The TrueBeam unit provides cutting-edge imaging, tracking and patient positioning technologies, while safely delivering high doses of radiation in a relatively short amount of time, even in close proximity to the spine (See Figures).²

Dr. Rosenberg notes, “With this newer device, patients undergo only one to three radiotherapy sessions. For very ill patients with limited mobility, this helps to minimize the burden associated with transportation and multiple hospital visits.” The high radiation doses are generally well-tolerated, as Dr. Rosenberg adds, “Clinically, I’ve noticed patients seem to experience less fatigue while other side-effects are comparable.”

For patients with metastatic spinal cancer, pain is frequently a common issue and can be related to the tumor itself or instability of the spine. Relief of pain and management of spinal instability are essential goals with this patient population. Dr. Zacharia explains, “The vertebrae often do not successfully fuse in these patients, due to the effects of radiation therapy, malnutrition and the patient’s poor general health. We thus opt for a less extensive approach to fixation and fusion, which minimizes unnecessary risks and post-operative morbidity.”¹ This modern approach combines the latest in radiation technology with a limited, but safe and effective operation to provide optimal patient outcome, and improved quality-of life in this patient population.